Chapter 4- Carbohydrates-2020_07df3a5806f712b76d8826efe1dd8534

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CARBOHYDRATES

SIMPLE SUGARS
• MONOSACCHARIDES:
• Glucose, Fructose, Galactose
• DISACCHARIDES:
• Sucrose, Lactose, Maltose

Monosaccharide
Glucose Fructose (fruit sugar) Galactose
Major monosaccharide in the
body
Also known as dextrose
In bloodstream called blood
sugar
Breakdown of starches and
sucrose
Source of fuel for cells
In sucrose
In fruit, honey, and highfructose
corn syrup
Converted into glucose in the
liver
In lactose
Converted to glucose in the
liver

Disaccharides
Sucrose Lactose Maltose
Major sugar in fruits and
vegetables
In Milk
In Cereals and grains
Made from glucose + fructose Made from glucose +galactose Made from 2 glucose units.

Polysaccharides
3,000 or more monosaccharides
Starch Glycogen Dietary Fiber
Amylose
Storage form of
carbohydrates in plants
Amylopectin
Storage form of
carbohydrates in plants
Storage form of carbohydrate
for animals and human
Found in the liver and
muscles
Undigested starch
Body cannot break the
bonds

Dietary Fiber
• Insoluble or Non-fermentable fiber
- Cellulose, hemicellulose, lignin
- Not fermented by the bacteria in the colon
• Soluble or Viscous fiber
- Gum, pectin, mucilage
- Fruit, vegetable, rice bran, psyllium seed

Soluble and insoluble fiber
(Viscous and Non-Fermentable Fiber)

Functional Fiber
• Fiber added to food
- Provides health benefits
• Prebiotics – Type of functional fiber
- Stimulate growth or activity of beneficial bacteria in the
large intestine

Carbohydrate Digestion

Effects of Cooking
• Softens fibrous tissues
• Easier to chew and swallow

Digestion of Carbohydrate
In the Mouth
• Salivary amylase
- Breaks starch to shorter saccharides
- Prolonged chewing
• Short duration in the mouth

Digestion of Carbohydrate
In the stomach
• Acidic environment
• No further starch digestion

Digestion of Carbohydrate
In the Small intestine
• Pancreas releases enzymes
- Pancreatic amylase
• Absorptive cells release
- Maltase
- Sucrase
- Lactase
• Monosaccharides are absorbed

Carbohydrate Digestion

Lactose Maldigestion
• Reduction in lactase
- Lactose is undigested and not absorbed
- Lactose is metabolized by large intestinal bacteria
• Causes gas, bloating, cramping, discomfort
• Primary lactose maldigestion
• Secondary lactose maldigestion
• Severe cases are called lactose intolerance

What To Do if You Have Lactose
Maldigestion or Lactose Intolerance?
• Determine amount you can tolerate
• Eat dairy with fat (some tolerate better fat free
products)
• Cheese & yogurt are usually well tolerated
• Use Lactase Tablets (supplements)

After Absorption
Liver can:
- Transform monosaccharide into glucose
- Release glucose back into the bloodstream
- Store as glycogen (or fat)

Functions of Carbohydrate
• Supplies energy
• Protein sparing
• Prevents ketosis
• Sweetener

CARBOHYDRATES ENERGY
1 GRAMME → 4 KILOCALORIES
Spares protein breakdown
Spares fat metabolism and prevents ketosis

BLOOD SUGARS REGULATORS
Hyperglycemia
Hypoglycemia
Insulin hormone
Glucagon hormone
Epinephrine hormone
High blood sugars
Low blood sugars
↓ blood sugars
↑ blood sugars
↑ blood sugars

Blood Glucose Control
• Role of the liver
- Regulates glucose that enters bloodstream
• Role of the pancreas
- Release of insulin
- Release of glucagon

Functions of Insulin
• Promotes glycogen synthesis
• Increases glucose uptake by the cells
• Reduces gluconeogenesis
• Net effect : lowers blood glucose

Functions of Glucagon
• Breakdown glycogen
• Enhances gluconeogenesis
• Net effect: raises blood glucose

Epinephrine / Norepinephrine
• “Fight or flight” response
• Breakdown glycogen
• Raises blood glucose

Dietary Fibers and Health

Health benefits of fibres
• Prevention & treatment of constipation
• Prevention of colon cancer
• Decreases blood cholesterol
• Helps regulate blood sugar (Diabetes)
• Helps in weight control by increasing satiety
Recommended intake: 20-35g / day

Cholesterol and (Soluble) Fiber
• Blood cholesterol indirectly decreased
Bile acid absorption reduced
• Risk for cardiovascular disease and gallstones reduced
• Insulin release decreased
- Decrease cholesterol synthesis in the liver
• Blood cholesterol lowered

Colon Cancer and Fiber
• High fiber /lower meats intake (especially red meat)
• Focus on fruits, vegetables, beans, and whole grains
• Higher-fiber foods are more nutrient dense

Glucose Absorption and Fiber
• Soluble fiber slows glucose absorption
• Better blood glucose regulation (Specifically beneficial
for diabetic patients)

Weight Control and Fiber
• Filling
• Low in kcal
• Longer satiety effect

Carbohydrate Needs
• RDA is 130 grams/day for adults
• Average intake ?
more active → > carbs
~ 100 of younger → > carbs
• Recommendations vary
45%- 65% of total calories
Focus on fruits, vegetables, whole grains

Recommended Dietary Fiber Intake
M adequate
intake
• AI is 25 grams/day for women
• AI is 38 grams/day for men
• (Goal of 14 grams/1000 kcal)
no daily
value
• DV is set at 25 grams for 2000 kcal diet
• Average U.S. intake:
Women
Men
14 grams/ day 17 grams/ day

soluble -1
in Solum
soluble
→
Solow
↓
,
as:÷%
[
sound

• > 60 grams/day
• Extra fluid needed
Too Much Fiber
vitamins + minerals →
Win fibre
,
feel full faster
& excreted
trapped
→
consume
cold
✗ need calories ( children ]
-Vegeta
top
✓ need
lose weight
• May decrease availability of some minerals
• Unmet energy needs in children

HOW TO CALCULATE FIBER INTAKE
Servings of vegetables x 2
Serving of fruits x 2.5
Servings of refined grains x 1
Servings of whole grains x 2.5
Serving of legumes x 7
Serving of nuts and seeds x 2.5
Add up all figures

added sugar
ketchup
sweet
juices
yogurt
chocolate
Recommendation for Simple Sugar Intake
• Low nutrient density
→ f-
offer
health benefit
energy
beyond
• Dental caries
• Added to food and beverages
• < 10% of total kcal/day with a maximum of 50 grams (12
tsp) per day—WHO
• Average U.S. intake: 16% of total kcal/day
~82 grams per day

SUGAR
• 1 teaspoon = 20 kcal
= 4 grams of CHO
• Recommendation: 10% of total calorie intake
Example : 2000kcal diet = 200kcal = 13 tsp.

SUGAR
• Brown sugar
• Turbinado sugar (raw sugar)
• Maple syrup
• Honey

• 55% fructose
High-fructose Corn Syrup
• Cornstarch mixed with acid and enzymes
• Starch is broken down to glucose
• Some glucose is converted to fructose
• Cheaper than sucrose
• Does not form crystals

Sugar in processed foods
• 1 Cup cola: 7 tsp sugar
• 1 tbsp ketchup: 1tsp sugar
• 1 cup sweetened yogurt: 7 tsp sugar
• 30 g chocolate: 4 tsp sugar

all have almost same
quantity of
sugar /
carbs
can
differ
in terms
of
minerals
41

Sugar Substitutes

-
-
-
Sweeteners
derived from sources
natural
d
↓
g. aim fruit
'
,
-
>
}
little
less sweet
need to put
minute amount ,

less
Sugar Alcohols
• Sorbitol, Xylitol, Maltitol
• ~2.6 kcals/gram
calories
.
507
sweet
as
almost
as
sugar
• Large quantities can cause diarrhea
• Do not promote tooth decay
• Used in gum candies
• Absorbed and metabolized slower

• First produced in 1879
Saccharin
• 180-200x sweeter than sucrose
• No potential risk in humans

2 amino acids → protein → calories
Aspartame (Equal , NutraSweet )
• Composed of phenylalanine, aspartic acid, and methanol
• 180-200x sweeter than sucrose
• 4 kcal/gm
→ loses
• Not heat stable
sweetness at high temp ,
• Complaints of sensitivity
- Headaches, dizziness, seizures, nausea, etc.
f- exceed that amount per day
• Acceptable daily intake: 50 mg per kg body weight
(FDA) (~14 cans of diet soda for average adult per day)
• Warning label for Phenylketonuria (PKU)

• 600x sweeter than sucrose
Sucralose (Splenda )
closest task to sugar
• Substitutes chlorines for hydroxyl groups on sucrose
• Heat stable
• Tiny amount digested
• Excreted in the feces

Neotame
• FDA approved for general-purpose sweetener
• Similar structure to Aspartame
• Is not broken down in the body
• 7,000-13,000x sweeter than sucrose
• Heat stable
• Safe for use

Acesulfame-K (Sunette )
• Approved by FAD
• 200x sweeter than sucrose
• Not digested by the body
• Heat stable
• Diabetisweet used in baking

Tagatose
• Altered form of Galactose
• Almost same sweetness as sucrose
•
similar
to sugar
alcohols
Btu taste
no die , ✓ hee
• 1.5 kcals/gram
• Does not increase glucose levels
• Does not cause tooth decay
• Is fermented by the large intestine

Stevia (Sweet Leaf ® )
• 100-300X sweeter than sucrose
• Provides no energy
• Generally recognized as safe (GRAS)